Oscilloscope?

[Jan Schultink]

Do you guys use one? Hardware? Software? Which one should I get? My recent purchase of a mkI DX7 made me dig through all kind of esoteric books about FM and I would love to add this tool to visualize what I am doing.

[chysn]

I use Signal Spy for iPad for audio signals. It has an oscilloscope and a spectrum analyzer. I find that a spectrum analyzer contains more useful information than an oscilloscope for musical applications, and your $100 handheld o-scopes don't do that.

The case for the spectrum analyzer is pretty easy: It's hard to "see" the correlation between waveshape on a scope and sound without a lot of experience. A square wave might not look very square on the scope, but when you flip over to the spectral analyzer, you see the expected peaks at odd-numbered harmonics. Plus you can see all the extra harmonics introduced at lower levels. IMO, it's far more valuable information, even though it's probably not as cool-looking.

I think this is especially true of DX7 synthesis, where you want to see how your levels and ratios are affecting spectrum. You can approach the shapes you want without so much hunting in the dark.

[Jan Schultink]

Yes, I meant a device that can do both, including spectrum analysys

[chysn]

I haven't been able to find a hardware spectrum analyzer with a low enough cost. Handheld ones start at maybe $400, and it's hard to justify that as it's the price of one or two modules. And we don't need to worry about gigahertz for audio, so tablet apps are probably the best tool for the job.

I used the spectrum analyzer a lot when I was trying various oscillators. It was really useful for seeing how the mysterious Timbre, Order, and Symmetry controls on a Buchla 259 clone work. Now that I've made my final long-term oscillator choice, I don't use the app much anymore.

I'm keeping my eye open for an old-timey analog Heathkit laboratory oscilloscope like my uncle had. Those things go a long way toward making any room look awesome.

[DavidDever]

I use a BitScope BS10U that was recommended by a friend: http://www.bitscope.com/product/BS10

Can be networked via a Raspberry Pi, and works on Linux (including Raspbian!) / macOS / Windows.

[BobTheDog]

For audio stuff you could just use some free plugins in your DAW, Voxengo do a free version of Span: http://www.voxengo.com/product/span/ and Amanda Montanez a free oscilloscope: http://armandomontanez.com/smexoscope/

For this approach you want an audio interface that gives you a high sample rate

I have a BitScope and as David says the bit scope stuff isn't bad although the software is a bit lacking.

I recently got Rigol DS1045Z scope as well, it can be hacked to get 100Mhz and has some pretty good functionality including FFT, there is a good overview video here: the main problem with the scope is it's loud fan, I'm going to open it up and replace the fan when I get round to it. Highly recomended though if you want to go beyond audio into electronics.

[Jan Schultink]

Thank you, I installed SPAN for the moment, and will look into hardware options. Availability and pricing is always poorer here in Tel Aviv than in the US.

[Jan Schultink]

I recently got Rigol DS1045Z scope as well

I did not see any examples of the spectrum analyzer in the videos, can this device do this?

[BobTheDog]

I haven't tried it but I'm pretty sure there is an FFT maths function, I will check it a bit later and get back to you...

[BobTheDog]

HI,

Just has a play, there is an FFT module in the maths functions.

I have included a couple of pics using Hanning FFT on a square wave of 1khz. One is up to 300Khz and one up to 30Khz.

Its useable but no where near as good as SPAN for audio unless you want to look up at the high frequencies.

[Jan Schultink]

Thank you!